museum piece vs reliquary

museum piece

noun
  • A very old item, especially an obsolete piece of technology. 

reliquary

noun
  • An object that sustains the memory of past people or events. 

  • A container to hold or display religious relics. 

  • A person who owes a balance. 

How often have the words museum piece and reliquary occurred in a corpus of books? (source: Google Ngram Viewer )